1. Field of the Invention
The present invention is directed to the field of expanded edible products having a porous, foamed, or cellular interior and, most significantly, a self-sealing surface or skin.
2. Description of the Related Art
Expanded food products, broadly understood, means food products that have air pockets. Such products are particularly popular in the confectionery field. Many such expanded food products and methods of making them are known in the art and are commercially available.
One method of forming an expanded product is known as chemical aeration. This method may use, for example, bicarbonate of soda to cause a chemical reaction forming gas that creates pockets as it escapes from the interior of the recipe. The resulting center material has a cellular matrix. The familiar xe2x80x9crisingxe2x80x9d of bread is another example. In this case, a chemical reaction involving yeast results in the formation of a porous cellular structure. In many instances, it is desirable to avoid a chemical aeration process in the manufacture of an expanded food product, either to avoid the use of the additional recipe components, or to avoid the by-products that are left behind.
A technique for avoiding chemical aeration has been the use of vacuum oven technology to prepare expanded food products by vaporization of moisture in the pre-expanded mix.
It has been observed that the cellular structure of expanded products extends to the surface of the products, so that holes appear in the surface of the article. The result is that these expanded products tend to have a more fragile surface. When these products are jostled together, such as in a package or during manufacture, tiny particles are broken off as dust. This problem, referred to herein as xe2x80x9cdusting,xe2x80x9d has limited the development of a full range of expanded food products.
Potential solutions to the problem of dusting typically include coating the formed expanded food product to obtain a surface having structural integrity. However, it is often difficult to coat or perform other process steps on an expanded product because of the fragile surface. Thus, an expanded product with a self-sealing surface that is resistant to abrasion and which does not crumble during packaging and shipment represents a solution to a long-felt need in the industry. Such an expanded food product having a substantially self-sealing, structurally stable surface would avoid the problem of dusting without the necessity of performing additional steps.
U.S. Pat. No. 4,104,405 discloses that expanded confectionery, such as marshmallow, may be prepared using a formulation mix containing a film forming agent and beating air into the mix with a whipping operation. Expanded confectionery, however, prepared by vaporization of moisture and having a self-sealing surface or skin are not disclosed or suggested.
It would be highly desirable to provide an expanded food product, having low caloric density and a light aerated texture, prepared without using chemical aeration or requiring pre-whipping, and having a structurally stable surface achieved without coating or treatment.
This invention is directed to expanded food products prepared by expanding food formulations comprising a structure-enhancing hydrocolloid, water and a bulking agent. At least one component of the food formulation is crystallizable. The expanded products comprise a cellular inner portion containing pores formed by vaporization of at least a portion of the water and a substantially self-sealing surface portion having a greater density than the inner portion. The inner portion has a xe2x80x9ccenter densityxe2x80x9d and the self-sealing surface portion has a xe2x80x9csurface density,xe2x80x9d and the ratio of the center density to the surface density ranges between about 1:1.25 to about 1:2.5.
Self-sealing expanded edible products according to the invention can have a crispy, aerated structure which dissolves rapidly to release an intense flavor, while at the same time exhibiting an increased resistance to abrasion. Aeration may be achieved without chemical byproducts, such as sodium, which is tremendously important for those people on a low-sodium diet and is also important to avoid the excessively salty taste associated with such byproducts.
This invention is also directed to a method of preparing the above-described self-sealing expanded edible products.